The invention relates to emergency services and, in particular, to providing alternate routing information to an answering point of an emergency services network. More particularly, this invention provides nominal emergency services call processing cases with information to allow a call taker to understand the call processing logic used for a specific call. Also, in an alternate routing scenario where a primary answering point is not available to handle an emergency call, the emergency services network routes the emergency call to an alternate answering point and also provides alternate routing information to the alternate answering point indicating a reason for routing the emergency call to the alternate answering point instead of the primary answering point.
In the United States, basic 9-1-1 service and Enhanced 9-1-1 service (E9-1-1) were developed for landline-based telephony as emergency reporting services where a calling party can dial 9-1-1 in emergency situations. When an emergency call, such as a 9-1-1 call, is placed over a telephone network, the telephone network identifies that the call is an emergency call and routes the call to a selective router, which is a dedicated 9-1-1 switch in an emergency services network. The selective router processes trunk that the call arrived on or the directory number of the calling party who placed the emergency call to select a Public Safety Answering Point (PSAP, also known as a “Public Safety Access Point”) to handle the call. The selective router then routes the emergency call to the selected PSAP.
The call is answered at the PSAP by a call taker. The call taker converses with the calling party to determine information on the emergency situation. For instance, the call taker may ask the calling party for his/her name, the nature of the emergency, the location of the emergency, etc. The call taker then contacts emergency personnel to respond to the emergency based on the gathered information. E9-1-1 has the additional features of automatically providing the call taker with some information on the calling party. For instance, E9-1-1 service includes the features of Automatic Number Identification (ANI) and Automatic Location Identification (ALI). With ANI, the call taker at the PSAP is automatically provided with the telephone number of the phone placing the emergency call to allow for call back. The PSAP also uses the ANI to query the ALI database for information on the physical location of the calling party's phone. The ALI database stores records mapping telephone numbers to information on a physical location (such as a street address). Responsive to the query from the PSAP, the ALI database returns the location information for the calling party. With the telephone number and the location information, the call taker can more effectively handle the emergency call.
The logic in a typical selective router is as follows. Responsive to receiving an emergency call, the selective router determines whether trunk-only routing is enabled. If trunk-only routing is enabled, then the selective router routes the emergency call to a PSAP identified by a relationship with the trunk over which the selective router received the emergency call. If trunk-only routing is not enabled, then the selective router performs selective routing based on the calling party number. In the selective routing process, the selective router may query a selective routing database based on the calling party number to acquire an Emergency Service Number (ESN). Based on the ESN, the selective router builds a list of PSAP's (or other destinations) to handle the emergency call. The selective router identifies one of the PSAP's as the primary PSAP, and the other PSAP's as alternate PSAP's.
The selective router then attempts to route the emergency call to the primary PSAP. Before routing the emergency call, the selective router determines whether the primary PSAP is available to handle the emergency call. For instance, the selective router determines whether the PSAP is busy or has been abandoned. If the primary PSAP is available, then the selective router routes the emergency call to the primary PSAP. If the primary PSAP is not available, then the selective router performs alternate routing. The selective router identifies an alternate PSAP to handle the call, and determines whether the alternate PSAP is available to handle the emergency call. If the alternate PSAP is available, then the selective router routes the emergency call to the alternate PSAP. If the alternate PSAP is not available, then the selective router performs alternate routing again.
In a traditional emergency services network, the selective router is coupled to the PSAP over a circuit-switched network. More particularly, the selective router is coupled to the PSAP by redundant CAMA trunks. CAMA trunks have limitations in that only a small amount of information can be passed over these trunks from the selective router to the PSAP when routing the call. Typically, the selective router only passes the ANI to the PSAP over a CAMA trunk. The PSAP thus has to access the location information for the calling party from an ALI database based on the calling party number.
More recent implementations of emergency services networks implement packet-switched technology in place of circuit-switched technologies. More particularly, the selective router is connected to the PSAP's over a packet network, such as an IP network. The use of a packet network allows the selective router to pass more information to the PSAP than can be done over a CAMA trunk. As one example, the selective router can pass location information to the PSAP over the packet network. As another example, the selective router can pass additional information about the emergency situation to the PSAP over the packet network, such as that the emergency situation is at a hazardous location.
One problem with present emergency services networks, whether circuit-switched or packet-switched, is that a PSAP receiving an emergency call is not informed as to whether that PSAP is the primary PSAP or an alternate PSAP in the selective routing process. Also, a call taker at the PSAP receiving an emergency call is not informed as to the reason that he or she is receiving the call. Such reasons include, but are not limited to, the primary PSAP reached its call handling capacity or has been abandoned. In a circuit-switched network, it is not feasible to transmit such information over the CAMA trunks between the selective router and the PSAP. In a packet-switched network, no process exists or has been suggested to inform the PSAP as to whether the PSAP is the primary or an alternate.